Means for extracting cores of soil from the ground



Oct. 28, 1952 w. KJELLMAN ETAL 2,615,680

MEANS FOR RXTRAOTING cOREs OR son. FROM TRE GROUND Filed March 29, 1948 l 2 srmETsl-SHEET 1 Oct. 28, 1952 w. KJr-:LLMAN ETAL MEANS FOR EXTRACTING CORES OF SOIL FROM THE GROUND 2 SHEETS-SHEET 2 Filed March 29, 1948 1N VENTOR ATTORNEW( Patented Oct. 28, 1952 Walter AKjell/man, Stockholm, and Torsten Karl y Edmund Kallstenius,\Lidingo, `Sweden v f l Application Marchas, 194s, serial Nd. 17,756

t .l f Insweden April 2, 1947 1 Our. invention relates to a method and a' device lorextracting cores of soil from the ground.

. yIn the examination .of grounds `it wouldbe of great value to be able to extract long andfcontinuous cores of soil with undisturbed structure. lf, to this end, an ordinaryy tube is driven into the ground, it will be found, however, that the tube will, to a certain degree, vdraw with it downwards the core of the soil formed therein, this `being a result of the friction and adhesion on the inside of thetube. Asa consequence, part of the vearth mass immediately below the lower mouth ofthe tube will be forced away-,laterally instead '.Ofentering the tube.Y The forcing away :will be the more complete the .softer this mass isfand the harder and longer the already formed core. For. this reason, the natural earth strata will be present in the core at a thickness reduced to .an

unknown extent and with a structure disturbed to. an unknown degree. lAsa result'of said forcing away, very short cores only can be obtained inV most kinds of earth rby means of theabove named method.

:f5 Attempts have been made 4to ,eliminate these inconveniences, but as far as weare aware hither- Atofno method suitable for extracting long cores :has been found. f

- lItis the object of this invention to provide a -method and means which render possible-thc '..extraction' of long and continuous borer along the line A in Fig. 1a; Figs. 3b and 3c` are similar sections with modified arrangements of the supply rolls. Fig. 4 is a detail vertical sectional view showing the sections of the cylinder connected together, and Fig. 5 is a sectional view taken substantially along the line 5f-5 of Fig. 4. The borer illustrated comprises. three main '.partspnamely, a lower part which maylibe termed cylinder, an upper elongation thereof which may be termed tube, and a plunger movable in the cylinder and tube. The cylinder comprises in turn an inner sleeve 5, an outer sleeve 9i, acutter .holder-I3 and an easily exchangeable cutterk I4. yThe .tube which by .meansof threaded sockets 2 I,

,-Eig.1;2, is` joined from portions preferably having :Ealength of 4-three toisix-feet, consists of apreplunger I2.

cision drawn inner tube 3 and-.an outer tube2, said tubesbeing, for instance, soldered to .each

other. `A pin 4 and radially displaceable locking bolts 6 ,are provided in the upper portioriofl the Inthe positionv shown" in'Fig. la, the'bolts 6 secure the plunger to the cylinder, whereas the plunger is disengaged in theposition ,shown in Figglb. The supply rolls I arefplaced in recesses .3| in the wall of the cylinder `and retained by a ring 8.' From the.rolls,:the metal foils. IIlrun downwards between the outersleeve m9 and the inner sleeve 5 and are deflected by the .lower edge of the inner sleeve, and then'v extend upwards between the inner sleeve and the plunger I2 to which the ends of the 'foils' are vattached by a securing `member II. 4It will be ynoted `.from

'Figures4- and 5 thatthe'force from the .tube'.2

andthe inner sleeve 5 is transmitted to the outer y.sleeve Sby the threads 30 which interconnect the sleeves 5 and 8. The inner sleeve 5 maybeprol vided with a number offaxial recesses 3| through which the foils passdownwardly from the supply rolls'I (Fig-.5). f'

. Withthe parts in the positionsishown Fig. .1a,.-the lborer is driven down from the surface o'f thev ground to the level at which the extraction of the core has toy start. Thereupon, a rodLor .chain I8 is passed down intothe tube.2,\3.. rBy ,means of` a gripping device 22 having hooks 5I,

the chain I8 engages the pin 4which is lifted so was to disengage the plunger from the-cylinder. yThe plunger. is .then held ata constant level ,by

means of the chain I8, a stretching devicefIG and the boreframe I'I,Fig. 2, whereas the tube and the cylinder are driven down by means ofp-a jack 20. As will be evident from Fignla,A a core of the soil will be cut outand gradually coated'with vthe. foilsA unwound from the supply rolls .'I.v Every time when the tube'2 4is to be elongated, the chain I8 is fixed to the uppermost tube portion I8 by '.meansl of a locking device, a new tube portion 2,

3 is mounted on the tube, and the locklngdevice ischanged over again, thus preventing vertical f movements andstresschanges in the core of the soil. As a rule, the above named arrangement ls -suflicient for maintaining the plunger at a conpinvls given a shape somewhat different from that shown in Fig. 1. I i After a core of desired length has been cut out,

the chain I8 is released from the boreframe and secured to the boretube. Then the borer is lifted by means of the jack, and the core will follow upwards together with the borer. Devices of the type used in common test borers may be provided for cutting off the core from the underlying soil prior to the lifting of the boretube, and devices may also be used for preventing the core from falling out of the borer during the upward movement thereof. Experiments made have proved, however, that such devices can be dispensed with even in pure sand below the level of the ground water.

After the borer has been drawn up, the cylinder is unscrewed and cleaned and charged with a new set of supply rolls, whereupon it is ready for the next boring operation. The core of soil is dragged out of the tube by means of the plunger and the foils which are then taken oif from the core and, if possible, used again. Then, the core is examined, and typical specimens are cut out and sent to the laboratory. If, instead thereof, it is desired to send the entire core to the laboraltory, the core may be left in the boretube which by means of suitable sockets may be divided into portions suitable for the transport and having their ends closed by covers and sealing means.

Alternatively, the core together with the foils may vbe dragged over into separate longitudinally divided or undivided transport tubes.

Preferably, the inner diameter of the bore-cy1 yinder is somewhat smaller than the inner diameter of the boretube. As the core enters the tube, the horizontal pressure on the core and, consequently, the friction between the foils and the tube will be reduced as a result thereof. In this manner, the pull acting on the foils is decreased to a large extent, and as a result thereof the maximum length of the core obtainable in one operation is increased. To the same end, it isl advantageous to provide for lubrication between ythe foils andthe wall ofthe tube.

The borer may be driven into the'ground by pressure as shown in Fig. 2 or by ramming. In hard grounds it may be necessary to use an outer casing and to remove the earth which enters the `space between the boretube and said casing, by

any suitable known method, such as jetting.

.Care has to be taken in this case so as not to disturb the earth below the core.

The device shown in Fig. l'may be simplifiedl by omitting .the guide edge and having'the foils :passfrom the supply rolls directly -to the core -will become rather blunt will-not result in'any inconvenience.

The inner diameter of the borer'shown in Fig.

41 may, for instance, amount to 2 to.3 inches, and

eight foils maybe used having a thickness of one to two thousandths of an inch and consisting of -steel or soft iron or any other suitable material.

By means of such a--borer, very long cores, for

. instance 18 feet or even more, may be extracted in-an undisturbed condition from soils of a` character varying between soft mud, clay and compact sand, which was not possible hitherto. Y

With a borer which permits theextraction'of cores having a length of, for instance,A 18 feet, the operation may be as follows. The rst core is extracted from a hole extending from the ground surface down to a level at 18 feet, the second core is taken from a hole located near the first hole and extending from 16 to 34', the third core is taken from the first hole between 32 and 50', etc. Due to this overlapping, the ends of the cores. which are always slightly disturbed, can be cut oil, and a single undisturbed core can be composed, reaching from the soil surface down to the rm ground.

The axis of each supply roll may be located vhorizontally and either tangentially with respect to the core, Fig. 3a, or radially, Fig. 3b, or more or less obliquely, Fig. 3c.

In the embodiments illustrated in Figs. 3a and 3c, the supply rolls may be located at the same level above the lower mouth of the boring tube. In the embodiment according to Fig. 3b, the supply rollsare preferably located at two to four different levels.

As the foil passes round the guide edge, it will be buckled to a degree which increases with the width of the foil compared with the diameter of the core. Tests made with steel foils and a core diameter of about 21/2 inches have proved that in this instance the width of the foil may be about 1% at the most without 4the foil being damaged by buckling. From this it follows that under the conditions indicated at least six foils must be used if it is desired entirely to cover the circumference of the core. This is, however,l not necessary, it being on the contrary suitable to 'provide for a small clearance between adjacent foils lso as to prevent the foils fromcontacting leach other and being damaged .at their edges. It may,;how ever, Aprove suitable to use more foils vthan Vindicated above, since the thickness of the wall of the borer `may be reducedinthis case, resulting in amore undisturbed structure of the core.

From the above Ydescription .it `will .be evident that while the 4borerisdriven down, sliding will occur between the borer and the foils, and the friction ensued therefrom will exert a pull/.0n the .foils without affecting the core. If for some reason the core should tend to move upwards or downwards, such movement is prevented by the friction and adhesion which in such .'casewill occur between the foils and the core. Friction and adhesion which hitherto have been thel principal cause of all difficulties, are thus, bymeans of the foils, turned into useful forces which cause the .earth strata entering the borer to maintain their natural' thickness and structure.

According as the core .during .the downward movementof the borer is'formedby'the cutterat the lower end of the borer, eachfoilis continuously fed in between the wall of the 4borer and `the core via the guide edge located above-the cutter. .either from the upper end of the borer through a passage'in'the wall of the boreror from supply The foils are supplied to the guide vedge rolls'provided in a recess in the'wall ofthe borer above the guide edge. The foils in the supply rolls may be wound on reels roriupon themselves.

According to 'the lengths, widths and -thlck- Ynesses of the foils used, the dimensions'of the supply-rolls will vary vand thereby also the most suitable -arrangement of the same in the wallof boretube comprising ,two interspaced fconcentric walls, the outer one of said walls extending downwardly beyond the inner wall, a boring cutter secured to the lower end of said outer wall, circumferentially spaced supply rolls carried by said boretube above the lower end thereof, foils mounted on said rolls and extending downwardly into the space between said walls, the lower end of said inner wall being shaped as a guide and deilecting edge for foils fed from said supply rolls through said space to the inside of the boretube, and means for retaining the foil ends within the boretube at a substantially constant level during the downward movement of the boretube.

2. A borer for extracting cores of soil from the ground, comprising a boretube constructed and arranged to be driven into the ground and therebi7 to cut out a core of soil, the lower portion of said lboretube comprising two interspaced concentric into the space between said walls, said foil supply rolls being rotatable about horizontal axis, the lower end of said inner wall being shaped as a guide and deecting edge for foils fed from said supply rolls through said space to the inside of the boretube, during the downward movement thereof so as to cover at least part of the core entering the boretube, and means for retaining the foil ends within the boretube at a substantially constant level during the downward movement of the boretube. l

3. A borer for extracting coresof soil from the ground, comprising a boretube constructed and arranged to be driven into the ground and thereby to cut out a core of soil, means for successively feeding 4a number of axially extending foils in between the wall oi said boretube and the core entering said boretube, means for guiding and deecting the lower end of the foils to the inside of the boretube, a member axially movable in said boretube, means for securing the foil ends Within the boretube to said member, means for retaining said member at a substantially constant level during the downward movement of the boretube, and means for connecting said member to the boretube during the upward movement thereof.

WALTER KJ ELLMAN Y TORSTEN KARL EDMUND KALLSTENIU REFERENCES CITED The vfollowing references are of record in th le of this patent:

UNITED STATES PATENTS Number Name l Date f 1,808,009 Scott June 2, 1931 1,849,345 f Cormier Mar. 15, 1932 2,234,286 Stokes Mar. 11, 1941 FOREIGN PATENTS Number Country Date 42,125 Netherlands Dec. 15, 1937 

